1. Field of the Invention
The present invention relates to processes for the preparation of dicyclopentenol esters.
2. Discussion of the Background
Various processes are known for the preparation of dicyclopentenol esters having the following formula: ##STR2## wherein R is a C.sub.1-12 alkyl group, an aryl group, or a substituted aryl group. In general, all these processes start with the same raw materials: cyclopentadiene and an organic acid. They all require however expensive and time-consuming processing steps.
Processes which use solid catalysts require a filtration operation. Processes using liquid catalysts require a neutralization and an aqueous extraction operation.
In both of these processes, the catalyst system used is completely lost. This causes, among other problems, the problem of disposal and work-up. Due to these additional processing steps, the cost of the end product becomes very high.
In all existing processes, prior to product work-up, the catalyst systems are either destroyed or removed from the reaction mixture to (1) prevent the ester from splitting back to the starting materials, and (2) to prevent the reaction product from further resinifying.
It is known that of various kinds of acids, such as sulfuric acid, peracetic acid, or organic sulfonic acids, boron fluoride and boron fluoride phosphoric acids can also be used as esterification catalysts (U.S. Pat No. 2,457,157). However boron fluoride has the undesirable property of catalyzing the oligomerization of olefinic compounds (see F. H. S. Booth and D. R. Martin in Boron Trifluoride and its Derivatives, John Wiley and Sons, Inc., 1949). In the case of dicyclopentenol ester, oligomerization leads to increased resin formation.
In view of the usefulness of dicyclopentenol esters, there is thus a strongly need for a more efficient process for producing these materials.